/Library/LaunchDaemons/ is where the .plist files defining 'User
Daemons' that are launched as system startup are kept. Some other
useful locations: ~/Library/LaunchAgents for each user, and
/Library/LaunchAgents for all users.

KeepAlive
Don't restart the service; this way of using fossil works by starting
it in response to a request on port 8081.

Label org.fossil-scm.service
names the service, so is can be started sudo launchctl load and
stopped using sudo launchctl load